newbie questions

Hey guys, all right i have been having a rattling in my xj and sounds like it is coming from my transmission. It only happens when it is engaged in drive and i sitting at stop light. Now, i researched the probelm and it sound like it is my linkage chain. I was wondering how much it would cost for me to fix on my own or should i use my warranty to fix it. Thanks alot guys!!

I had a similar Mystery Noise for four years and until yesterday no one but me and my wife could hear it. It was also a rattling noise that only happened in gear while not moving. My mechanic put it up on the lift with me in the seat, car in drive, and foot on the brake. it turns out that one of the hangers for my exhaust was resonating and causing vibration. He did something to it with a little pry bar and I no longer have a Mystery Noise! it drove me nuts.

I know this is a very old post but I felt compelled to answer it anyway.

I had a horrible rattle scrap noise when I first started my XJ when I got it used. It would come back occasionally when I shifted and gave the vehicle gas, the shift lever would also swing out to the right when it did it.

Turned out the Driver's side Motor Mount was literally torn in half, the torque from the motor was lifting the whole engine/trans and rotating it right, pivoting on the passenger side Motor Mount. That caused the fan to scrap on the fan shroud.

Try to recreate the noise as you inspect the drivetrain and try to isolate the noise to find the problem. It would be a shame to pull apart a perfectly good XFER Case, just to find out the noise was $5 exhaust hangar or $20 Motor Mount.

might be the cat rotted out. Does it rattle when you start it or turn it off?

No idea if this will help you.

When I replaced my exhaust manifold my exhaust was moved a couple of mm to the rear due to slight difference in size original and replacement manifold. I did not notice that of course. However, when driving I found a 'new' rattle whenever I would stop at a traffic light or accelerate up-hill. I was utterly confused about it for about a week or so, then I decided to simply check the whole exhaust alignment. Turned out that the exhaust pipe, the last bend, was rattling against a flange of the fuel tank. To temporarily fix that you can simply bend the flange a little (that's what I did and worked fine), and when I had my muffler replaced I had them make sure that there was ample room between the exhaust pipe and the flange. Problem fixed!

So my advice is to check the alignment of the exhaust, just crawl under the car and see if you see it getting close to anything, and if so, see if there is any wear on the pipe that would indicate mechanical contact. It's worth the effort I think.

Good luck!